The present invention converns a device for the generation of negative pressure inside a cylindrical roll mantle of a revolving roll. The roll comprises a roll mantle provided with through holes, grooves, or equivalent and confining a suction chamber in the interior thereof, in which negative pressure can be generated by suctioning air out of the suction chamber. A suction flow directed towards the suction chamber prevails in the holes, grooves, or equivalent of the roll mantle.
Suction rolls are needed in several locations in paper machines. For example, suction rolls are used as guide rolls for felt, wire or paper. In particular, suction rolls are indispensible in the drying section. In prior art suction rolls presently being used, the negative pressure in the suction chamber situated inside the roll mantle is generated by means of external equipment for the generation of negative pressure, which is arranged so that the equipment suctions air out of the suction chamber through a separate pipe system and thus produces negative pressure in the suction chamber.
The roll mantle is most commonly provided with holes or with grooves extending through the roll mantle, with the air entering into the suction chamber of the roll through these holes or grooves. Drawbacks of the present equipment for the generation of negative pressure are the complexity of the equipment, as well as very high requirement of power. For example, with a 9.5 m. wide press-suction roll, the required suction power is of an order of 900 kW, which causes a very high annual operating cost.